[Purposes] This study investigated the spatial distribution characteristics and impact factors of non-point source pollution of Tieshan Reservoir Basin, so as to provide reference for water quality protection and non-point source pollution control for this basin. [Methods]A soil and water assessment tool (SWAT) model of the Tieshan Reservoir Basin was established to analyze the spatial distribution characteristics of the emission intensity and contribution ratio of non-point source pollution of total nitrogen (TN) and total phosphorus (TP). Besides, the non-point source pollution under three different land use scenarios was also studied. [Findings] The established SWAT is of good precision in simulating the water flow and pollutant transport processes in Tieshan Reservoir Basin. The non-point source pollution of TN is mainly from the applied fertilizers, while the non-point source pollution of TP is mainly from the rural domestic sewage and the applied fertilizers. The non-point source pollution of TN and TP in Tieshan Reservoir Basin decreased by 49.26% and 86.66%, respectively, from 1995 to 2015. [Conclusions] For the Tieshan Reservoir Basin, the “grain for green” program and the population centralized resettlement and relocation have positive impacts in decreasing non-point source pollution of TN and TP.